refactor: rebuild logger to be static

Fixes #4

src/common.ts

@@ -13,15 +13,17 @@
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
 
- /**
-  * A recursive partial object
-  *
-  * Copied from https://stackoverflow.com/a/51365037
-  */
+/**
+ * A recursive partial object
+ *
+ * Copied from https://stackoverflow.com/a/51365037
+ */
+import {Transport, VerifiableTransport} from './Transport';
+
 export type RecursivePartial<T> = {
   [P in keyof T]?: T[P] extends Array<infer U> ?
-  Array<RecursivePartial<U>> :
-  T[P] extends object ? RecursivePartial<T[P]> : T[P];
+    Array<RecursivePartial<U>> :
+    T[P] extends object ? RecursivePartial<T[P]> : T[P];
 };
 
 /**
@@ -47,3 +49,35 @@ export function deleteUndefinedProperties(obj: any) {
 
   return obj;
 }
+
+/**
+ * Checks if environment is Node.js
+ */
+export function isNodeEnvironment(): boolean {
+  return Object.prototype.toString.call(typeof process !== 'undefined' ? process : 0) === '[object process]';
+}
+
+/**
+ * Checks if environment is productive
+ */
+export function isProductiveEnvironment(): boolean {
+  return typeof process.env === 'object'
+    && typeof process.env.NODE_ENV !== 'undefined'
+    && process.env.NODE_ENV === 'production';
+}
+
+/**
+ * Checks if environment is Node.js and productive
+ */
+export function isProductiveNodeEnvironment(): boolean {
+  return isNodeEnvironment() && isProductiveEnvironment();
+}
+
+/**
+ * Check if a transport is a verifiable transport
+ *
+ * @param transport Transport to check
+ */
+export function isTransportWithVerification(transport: Transport): transport is VerifiableTransport {
+  return transport instanceof VerifiableTransport;
+}